Today was already forecast to see severe weather in Louisiana and Mississippi, but as of 1:08 PM eastern US time, storm cloud-tops coming in off the Gulf of Mexico have reached an astonishing 14km in altitude! That's 45,931 FEET in altitude!
The radar image above shows a significant area shaded in dark red (Circled area). That means cloud-tops have reached greater than 14km.
When thunderstorm clouds hit that height, they are able to bring intensely COLD air down to the surface. Cold air is heavier than hot air, and these clouds act like funnels to bring that cold to earth's surface. This greatly enhances convection and causes severe rotation - it's like an Assembly Line for Tornado activity.
People in Louisiana and Mississippi should be extremely vigilant today - this development does not bode well for them as far as Tornadoes.